1. Field of the Invention
The present invention relates to an image forming apparatus, such as a copier, a printer, a facsimile, a combined machine combining these apparatuses, etc. capable of subsequently forming toner images on an image bearer by repeating processes of discharging, writing, developing with dry type developer, transferring images onto transfer members, such as sheets, medium transfer members, etc., and cleaning. More particularly, the present invention relates to a toner scattering suppression apparatus capable of suppressing toner scattering from cleaning and developing apparatuses of the electro-photographic image forming apparatus.
2. Discussion of the Background
In a conventional electro-photographic system using an image forming apparatus, a discharging apparatus uniformly charges a surface of an image bearing member and a writing apparatus and subsequently writes and forms a latent image on the surface by irradiating a light while the image bearing member rotates. Then, a developing device applies toner so as to develop the latent image. The developed toner image is transferred by a transfer apparatus onto a transfer member, such as a sheet, a medium transfer member, etc. Finally, a cleaning apparatus removes toner remaining on the image bearer after image transfer. Then, the image forming apparatus prepares for the next image formation starting from discharging.
However, the rotation of the image bearer and of an internal rotation member cause a rising airflow and an internal air pressure increase in the developing and cleaning apparatuses each accommodating toner. As a result, the airflow leaks from slight gaps in the device at joined parts and toner leakage occurs together with the airflow. Thus, the image forming apparatus is contaminated internally and externally.
Typically, openings are arranged on the developing and cleaning apparatuses to drain air. Air filters are also attached to the openings so as to prevent toner passage and scattering therefrom. However, the air filter can be choked with the toner during usage, and therefore prevention from an increase in internal air pressure is not effective. Thus, dust collection is not effective and toner scattering likely occurs.
Consequently, the air filter requires periodical maintenance. Specifically, the air filter is cleaned by a cleaner or other appropriate substance, or washed to remove toner. Otherwise, the old air filter is replaced with a new filter.
However, two types of air filters are needed in the respective developing and cleaning apparatuses in such a conventional image forming apparatus. As a result, the number of replacement parts increases, and the cost of maintenance rises based on an increase in maintenance inventory.
Further, intervals of maintenance for air filters in the developing and cleaning apparatuses are different from each other in the conventional toner scattering prevention apparatus. Thus, a frequency of maintenance and accordingly an increase in cost results. In such a case, if an air filter with a long maintenance interval receives maintenance at the same time an air filter with a short maintenance interval, changing the long maintenance interval filter is wasteful.